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Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway

Electrical stimulation of the auditory nerve with a penetrating intraneural (IN) electrode in acutely deafened cats produces much more restricted spread of excitation than is obtained in that preparation with a conventional cochlear implant (CI) as reported by Middlebrooks and Snyder (J Assoc Res Ot...

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Autor principal: Middlebrooks, John C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer US 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6226412/
https://www.ncbi.nlm.nih.gov/pubmed/29968099
http://dx.doi.org/10.1007/s10162-018-0679-3
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author Middlebrooks, John C.
author_facet Middlebrooks, John C.
author_sort Middlebrooks, John C.
collection PubMed
description Electrical stimulation of the auditory nerve with a penetrating intraneural (IN) electrode in acutely deafened cats produces much more restricted spread of excitation than is obtained in that preparation with a conventional cochlear implant (CI) as reported by Middlebrooks and Snyder (J Assoc Res Otolaryngol 8:258–279, 2007). That suggests that a future auditory prosthesis employing IN stimulation might offer human patients greater frequency selectivity than is available with a present-day CI. Nevertheless, it is a concern that the electrical field produced by an IN electrode might be too restricted to produce adequate stimulation of the partially depopulated auditory nerve of a deaf patient. We evaluated this by testing responses to IN and CI stimulation in adult-deafened cats. Activation of the auditory pathway was monitored by recording from the central nucleus of the inferior colliculus (ICC). Cats deaf for 153–277 days exhibited a ~ 30 % loss of auditory nerve fibers compared to cats deaf for < 18 h. Contrary to our concern, measures of thresholds and dynamic ranges showed no significant deafness-related impairment of excitation by IN or CN stimulation. Surprisingly, however, temporal acuity decreased dramatically in these adult-deafened cats, as demonstrated by a marked decrease in the maximum rate of electrical cochlear stimulation to which ICC neurons synchronized to IN or CI stimulation. For instance, half of ICC neurons synchronized to IN stimulation up to 203 pulses per second (pps) in acute deafness, whereas that number dropped to 79 pps for chronic deafness. Such a loss of temporal acuity might contribute to the poor sensitivity to temporal fine structure that has been reported in human CI users. Seemingly, the degraded temporal acuity that we observed in cats was even worse than the fine-structure sensitivity of human CI users, suggesting that most patients experience some improvement of temporal acuity resulting from restoration of patterned auditory nerve stimulation by a CI.
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spelling pubmed-62264122018-11-23 Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway Middlebrooks, John C. J Assoc Res Otolaryngol Research Article Electrical stimulation of the auditory nerve with a penetrating intraneural (IN) electrode in acutely deafened cats produces much more restricted spread of excitation than is obtained in that preparation with a conventional cochlear implant (CI) as reported by Middlebrooks and Snyder (J Assoc Res Otolaryngol 8:258–279, 2007). That suggests that a future auditory prosthesis employing IN stimulation might offer human patients greater frequency selectivity than is available with a present-day CI. Nevertheless, it is a concern that the electrical field produced by an IN electrode might be too restricted to produce adequate stimulation of the partially depopulated auditory nerve of a deaf patient. We evaluated this by testing responses to IN and CI stimulation in adult-deafened cats. Activation of the auditory pathway was monitored by recording from the central nucleus of the inferior colliculus (ICC). Cats deaf for 153–277 days exhibited a ~ 30 % loss of auditory nerve fibers compared to cats deaf for < 18 h. Contrary to our concern, measures of thresholds and dynamic ranges showed no significant deafness-related impairment of excitation by IN or CN stimulation. Surprisingly, however, temporal acuity decreased dramatically in these adult-deafened cats, as demonstrated by a marked decrease in the maximum rate of electrical cochlear stimulation to which ICC neurons synchronized to IN or CI stimulation. For instance, half of ICC neurons synchronized to IN stimulation up to 203 pulses per second (pps) in acute deafness, whereas that number dropped to 79 pps for chronic deafness. Such a loss of temporal acuity might contribute to the poor sensitivity to temporal fine structure that has been reported in human CI users. Seemingly, the degraded temporal acuity that we observed in cats was even worse than the fine-structure sensitivity of human CI users, suggesting that most patients experience some improvement of temporal acuity resulting from restoration of patterned auditory nerve stimulation by a CI. Springer US 2018-07-02 2018-10 /pmc/articles/PMC6226412/ /pubmed/29968099 http://dx.doi.org/10.1007/s10162-018-0679-3 Text en © Association for Research in Otolaryngology 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Research Article
Middlebrooks, John C.
Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title_full Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title_fullStr Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title_full_unstemmed Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title_short Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway
title_sort chronic deafness degrades temporal acuity in the electrically stimulated auditory pathway
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6226412/
https://www.ncbi.nlm.nih.gov/pubmed/29968099
http://dx.doi.org/10.1007/s10162-018-0679-3
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